The hole angularity measurement is one which attempts to determine the perpendicularity of the center line of a hole or bore with respect to a plane that is parallel to the hole surface. The measurement bears particular importance for holes which are used in combination with screws and other similar fasteners as an indication of the resultant strength of the fastened structure. It is therefore desirable to provide a device for accurately measuring the angularity of a hole or bore.
In some industries, such as the aircraft industry, where mass production is impractical, many holes must be manually drilled. To improve quality control, a hole angularity measurement is taken on manually drilled holes to insure the integrity of the resultant structure. Accordingly, it is desirable to have a device for accurate manual measurement of the angularity of a drilled hole or bore.
Further, due to required manufacturing processes and procedures in the aircraft industry, some holes must be drilled, and the hole angularity measurement made, in small somewhat confined areas. Therefore, it is desirable to provide a hole angularity gauge which is small in size so that it can readily access these small confined spaces.
Prior hole angularity gauges have failed to meet the foregoing requirements. Further, at least one prior hole angularity gauge has required the user to rotate the gauge while taking the measurement to accurately determine the angularity of the hole. It will be appreciated by those skilled in the art that the requirement to rotate the gauge will lead to measurement inaccuracies and detract from the overall usefulness of the instrument. It is therefore desirable to provide a hole angularity guage which is easy to use.
As always, it is desirable to provide measuring apparatus which is not only accurately and easily used but also durable and easily calibrated.